Manpages

-bail (bail out of trial when size exceeds best size found

-blacken (zero samples underlying fully-transparent pixels)

-brute (use brute-force: try 176 different methods)

-c color_type of output file [0, 2, 4, or 6]

-check (check CRC and ADLER32 checksums)

-d directory_name/ (where output files will go)

-e extension (used for creating output filename)

-f user_filter [0-5] for specified method

-fix (salvage PNG with otherwise fatal conditions)

-force (write output even if IDAT is larger)

-g gamma (float or fixed*100000, e.g., 0.45455 or 45455)

-huffman (use only zlib strategy 2, Huffman-only)

-iccp length "Profile Name" iccp_file

-itxt b[efore_IDAT]|a[fter_IDAT] "keyword"

-keep chunk_name

-l zlib_compression_level [0-9] for specified method

-loco ("loco crush" truecolor PNGs)

-m method [1 through 177]

-max maximum_IDAT_size [default 524288L]

-mng (write a new MNG, do not crush embedded PNGs)

-n (no save; doesn’t do compression or write output PNG)

-new (Use new default settings (-reduce))

-newtimestamp (Reset file modification time [default])

-nobail (do not bail out early from trial -- see "-bail")

-nocheck (do not check CRC and ADLER32 checksums)

-nofilecheck (do not check for infile.png == outfile.png)

-noforce (default; do not write output when IDAT is larger)

-nolimits (turns off limits on width, height, cache, malloc)

-noreduce (turns off all "-reduce" operations)

-noreduce_palette (turns off "-reduce_palette" operation)

-old (Use old default settings (no -reduce))

-oldtimestamp (Do not reset file modification time)

-ow (Overwrite)

-q (quiet) suppresses console output except for warnings

-reduce (do lossless color-type or bit-depth reduction)

-rem chunkname (or "alla" or "allb")

-replace_gamma gamma (float or fixed*100000) even if it is present.

-res resolution in dpi

-rle (use only zlib strategy 3, RLE-only)

-s (silent) suppresses console output including warnings

-save (keep all copy-unsafe PNG chunks)

-speed Avoid the AVG and PAETH filters, for decoding speed

-srgb [0, 1, 2, or 3]

-ster [0 or 1]

-text b[efore_IDAT]|a[fter_IDAT] "keyword" "text"

-trns_array n trns[0] trns[1] .. trns[n-1]

-trns index red green blue gray

-v (display more detailed information)

-version (display the pngcrush version)

-warn (only show warnings)

-w compression_window_size [32, 16, 8, 4, 2, 1, 512]

-z zlib_strategy [0, 1, 2, or 3] for specified method

-zmem zlib_compression_mem_level [1-9, default 9]

-zitxt b|a "keyword" "lcode" "tkey" "text"

-ztxt b[efore_IDAT]|a[fter_IDAT] "keyword" "text"

-h (help and legal notices)

-p (pause)